Automated storage and retrieval system

ABSTRACT

A method and apparatus are provided for storing or retrieving items to/from a plurality of destinations areas. The items are loaded onto one of a plurality of independently controlled delivery vehicles. The delivery vehicles follow a path to/from the destination areas that are positioned along the path. The destination areas are configured such that the destination areas have a depth to accommodate a plurality of containers in a horizontal line one behind another. The containers may be releasable interconnected so that retrieving one of the interconnected containers displaces one or more connected containers.

PRIORITY CLAIM

This application claims priority to U.S. Provisional Patent ApplicationNo. 62/463,352 filed on Feb. 24, 2017. The entire disclosure of theforegoing application is incorporated herein by reference.

TECHNICAL FIELD

This disclosure relates to material handling systems for conveying oneor more objects from a first location to a second location and, moreparticularly, to automated storage and retrieval systems in which aplurality of containers are stored in a plurality of storage locationsin which some containers are behind other storage containers.

BACKGROUND

Many large organizations have extensive storage areas in which numerousand diverse items are stored and/or from which they are retrieved, forexample, to fill customer orders. Storing items into and retrieving theitems from the hundreds or thousands of storage areas requiressignificant labor to perform manually. In many fields, automated pickinghas developed to reduce labor cost and improve customer service byreducing the time it takes to fill a customer order. Frequently, thereis a trade-off between several variables in setting up a system, such asstorage density, accessibility, footprint, cost, just to name a few. Forinstance, increasing storage density in an automated storage andretrieval (ASR) system can reduce both the cost and the spacerequirements (“footprint”) for such a system. If the storage density ofan ASR system is too high, however, the reduced ease and speed withwhich individual items can be stored and retrieved may render the systemunsuitable for many applications.

By way of illustrative example, some ASR systems utilize a conveyingsystem that includes a plurality of independently operated vehicles.Such a system may be configured as an aisle with storage locations oneither side of the aisle and the vehicles travelling along a path withinthe aisle. The capacity of the system can be increased by making theaisle taller or longer. Alternatively, additional aisles may be added.However, in many situations, either the space may not be available forsuch as system or the cost may exceed the benefit of the increasedcapacity. Accordingly, in some applications there exists a need for anASR system with that increases the storage density at a lower cost andin a smaller foot print, without significantly affecting throughput ofthe system.

SUMMARY OF THE DISCLOSURE

In light of the foregoing, a system provides a method and apparatus forstoring and retrieving items. The system includes a plurality of storagelocations or destination areas, and a plurality of delivery vehicles fordelivering items to or retrieving items from the destination areas. Thedelivery vehicles follow paths to the destination areas.

The present invention may also provide an improved material handlingsystem in which storage containers in which independently operablevehicles are operable to deliver storage containers into and retrievestorage containers from storage locations having sufficient depth toaccommodate multiple storage containers in a horizontal orientation withone storage container positioned behind another. The system may includea track for guiding the vehicles along the track to the storagelocations. Additionally, the storage locations may be arranged so thatthe storage locations are vertically separated from one another. Forexample, the storage locations may be configured as an array of storagelocations in a plurality of rows or columns. The storage containers mayalso be releasably connectable with adjacent storage containers so thatdisplacement of a first storage container in a first storage locationdisplaces a second storage container within the first storage location.

The present invention also provides a material handling system forstoring or retrieving a plurality of items that includes a plurality ofindependently operable vehicles for delivering and retrieving items to adestination. Optionally, the system includes a track for guiding thevehicles. The system includes a plurality of storage locations wherein aplurality of the storage locations are vertically spaced apart from oneanother. The storage locations may be positioned along the track is thesystem includes a track. The system also includes a plurality of storagecontainers. One or more of the storage locations are configured toreceive a plurality of the storage containers. The storage containersinclude connectors for interconnecting connecting storage containersstored adjacent one another in a storage location. The connectorsconnect the storage containers so that displacement of one of thecontainers in a storage location discloses the interconnected containeror containers in the same storage location. The vehicles may include atransfer mechanism configured to transfer storage containers between thevehicle and storage locations. The transfer mechanism may be operable todisplace first and second interconnected containers when the first orsecond container is displaced relative to the vehicle.

According to another aspect the material handling system may include atrack system having a plurality of generally horizontal track sectionsspaced apart from one another. The track system may also include aplurality of generally vertical track sections spaced apart from oneanother. The vertical and horizontal track sections may beinterconnected to form a track loop.

According to yet another aspect, the present invention provides storagecontainers for a material handling system in which the storagecontainers have first and second connectors that are connectable toprovide a connection that impedes horizontal displacement of a firststorage container relative to a second storage container. The connectionof the first and second connectors may be sufficient to support theweight of the second container during horizontal displacement such thatdisplacing the first container horizontally displaces the secondcontainer horizontally when the first and second connectors areconnected. Additionally, the connection of the first and secondconnectors may permit vertical displacement of the first containerrelative to the second container.

According to another aspect, the system may provide storage containershaving first and second connectors for releasably connecting first andsecond storage containers wherein the first and second connectors areconfigured such that displacement of the first connector verticallyrelative to the second connector disconnects the first connector fromthe second connector.

The present invention further provides storage containers having firstand second connectors for interconnecting the storage containers withone another, wherein the first connector comprises a tongue and thesecond connector comprises a groove configured to receive the tongue.

According to another aspect, the present invention provides a storagelocation in which first and second containers are located and thestorage location is configured to house the first and second containersin horizontal alignment in which the first container is positioned infront of the second container. Optionally, the storage location may beconfigured so that when a delivery vehicle is aligned with the firstcontainer, the first container separates the second vehicle from thedelivery vehicle.

The present invention further provides a material handling system havinga plurality of storage locations each configured to store a plurality ofstorage containers. Optionally, the storage locations each have a depthand first and second one of the storage containers each have a lengthand the depth of the one storage location is at least as long as thecombined length of the first and second containers.

According to another aspect, the present invention provides deliveryvehicles for a material handling system and each vehicle has a generallyplanar platform for receiving the containers.

According to yet another aspect, the present invention provides amaterial handling system that includes a first rack of storage locationsspaced apart from a second rack of storage locations so that an aisle isformed between the first rack and the second rack.

Optionally, the material handling system may include a pick stationdisposed at an end of aisle. Vehicles may deliver storage containers tothe pick station so that operators can retrieve items from the storagecontainers at the pick station.

According to another aspect, the system may include vehicles that aredisplaceable within an aisle. The vehicles may comprise drive wheelsthat engage a track and racks of storage locations may be positionedrelative to the track so that storage containers project horizontallyinto the aisle beyond the track.

According to a further aspect, the present invention provides containersfor a material handling system and the containers contain one or moreengagement elements configured to engage a transfer mechanism ofvehicles that deliver the containers.

According to a further aspect, the present invention provides acontainer for use in a material handling system for storing orretrieving a plurality of items. The container includes a plurality ofwalls and first and second connectors configured to be connectable toform a releasable connection between two of the storage containers. Thestorage container may include an engagement element configured tocooperate with a transfer mechanism of the material handling system todisplace the storage container horizontally. Additionally, the materialhandling system may include storage locations and the container may havea length that is at less than or equal to half the depth of the storagelocation so that two of the containers will fit in the storage locationwhen the two containers are connected together. The first and secondconnectors may also be connectable to form a releasable connection.

Still further, the present invention may provide a combination of firstand second containers for use in a material handling system. The twocontainers may be similarly configured so that a first connector of thefirst container is connectable with a second connector of the secondcontainer to connect the two containers such that horizontaldisplacement of the first container by a transfer mechanism of adelivery vehicle displaces the second container. Optionally, theconnection of the first connector of the first container and the secondconnection of the second container impedes horizontal displacement ofthe first container relative to the second container.

The present invention also provides a method for storing and retrievingcontainers from a plurality of storage locations. The method includesthe step of driving a first vehicle with a first storage container alonga transport path among a plurality of storage locations. The firststorage container is unloaded from the first vehicle into a firststorage location. The first storage container is releasably connectedwith a second storage container in the first storage location. The firstvehicle is then displaced away from the first storage location after thestep of unloading.

According to another aspect, a method for storing and retrievingcontainers includes the step of disconnecting a first storage containerin a storage location from a second storage container in the storagelocation. Optionally, the step of releasably connecting comprisesdisplacing the first container vertically relative to the secondcontainer.

According to a further aspect, a method for storing and retrievingcontainers using vehicles includes the step of disconnecting first andsecond connected containers by displacing the first container verticallyrelative to the second container.

According to yet another aspect, a method for storing and retrievingcontainers using vehicles includes the step of loading a first storagecontainer onto a vehicle after a step of releasably connecting the firststorage container and a second storage container such that during thestep of loading the first storage container pulls the second storagecontainer toward the vehicle.

According to a further aspect, a method for storing and retrievingcontainers using vehicles includes the step of unloading a first storagecontainer into a storage location. The step of unloading comprisespushing the first storage container against a second storage containerto drive the second container deeper into the storage location. The stepof unloading may include the step of actuating an unloading mechanism onthe first vehicle to drive the first storage container off the firstvehicle.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing summary and the following detailed description of thepreferred embodiments of the present invention will be best understoodwhen read in conjunction with the appended drawings, in which:

FIG. 1 is a perspective view of a storing and retrieving apparatus;

FIG. 2 is a fragmentary side view, illustrating a track of the storingand retrieving apparatus illustrated in FIG. 1;

FIG. 3 is an enlarged perspective view of a vehicle of the storing andretrieving apparatus illustrated in FIG. 1;

FIG. 4 is an enlarged perspective view of a gate of the trackillustrated in FIG. 2;

FIG. 5 is an enlarged perspective view of a gate of the trackillustrated in FIG. 2;

FIG. 6 is an enlarged perspective view of a gate of the trackillustrated in FIG. 2;

FIG. 7 is an enlarged fragmentary view of a wheel of the vehicleillustrated in FIG. 3 and a portion of the track illustrated in FIG. 2;

FIG. 8 is a side diagrammatic view of a plurality of storage locationsof the apparatus illustrated in FIG. 1;

FIG. 9 is diagrammatic side view of storage containers in the storagelocations of the apparatus illustrated in FIG. 1;

FIG. 10A is a diagrammatic view of the storage containers illustrated inFIG. 9, showing a step in the process of moving a storage container fromone location to another;

FIG. 10B is a diagrammatic view of the storage containers illustrated inFIG. 9, showing a step in the process of moving a storage container fromone location to another;

FIG. 10c is a diagrammatic view of the storage containers illustrated inFIG. 9, showing a step in the process of moving a storage container fromone location to another;

FIG. 10D is a diagrammatic view of the storage containers illustrated inFIG. 9, showing a step in the process of moving a storage container fromone location to another;

FIG. 10E is a diagrammatic view of the storage containers illustrated inFIG. 9, showing a step in the process of moving a storage container fromone location to another;

FIG. 10F is a diagrammatic view of the storage containers illustrated inFIG. 9, showing a step in the process of moving a storage container fromone location to another;

FIG. 10G is a diagrammatic view of the storage containers illustrated inFIG. 9, showing a step in the process of moving a storage container fromone location to another;

FIG. 10H is a diagrammatic view of the storage containers illustrated inFIG. 9, showing a step in the process of moving a storage container fromone location to another;

FIG. 11 is a fragmentary perspective view of a portion of a storage rackof the apparatus illustrated in FIG. 1;

FIG. 12 is a fragmentary perspective view of a portion of a storage rackof the apparatus illustrated in FIG. 1 including a vehicle of theapparatus; and

FIG. 13 is a fragmentary side view of a releasable connection betweenstorage containers of the apparatus illustrated in FIG. 1, in which thestorage containers are connected; and

FIG. 14 is a fragmentary side view of a releasable connection betweenstorage containers of the apparatus illustrated in FIG. 1, in which thestorage containers are disconnected.

DETAILED DESCRIPTION

Referring now to the figures in general and to FIG. 1 specifically, amaterial handling apparatus adapted to store and/or retrieve items isdesignated generally 10. The apparatus 10 includes a plurality ofvehicles for transporting items along a transport path between a firstlocation and a second location. In some embodiments, consistent with thepresent disclosure, the first location is a storage location selectablefrom among a plurality of storage locations 50 in one or more storageracks and the second location is an article transfer station 300 whereitems may be picked, sorted and/or transferred from or to receptaclesfor storage, such as storage containers 80. The apparatus 10 moves items(or containers which contain items) along the conveying path.

In some embodiments, the apparatus includes a plurality of transportvehicles or vehicles 200 that travel along one or more pathways in anaisle 20 adjacent one or more racks 35, 40 that are configured to storea plurality of storage containers 80. For instance, as shown in FIG. 1,the aisle 20 may be an elongated aisle formed between a pair of racks35, 40 so that the vehicles move within the aisle along one or morepathways. A track 110 may provide one or more pathways within the aislefor the vehicles to travel to storage locations in the racks. Forinstance, an embodiment may include a front track 115 adjacent a frontrack 35 on one side of the aisle. A rear track 120 adjacent a rear rack40 may be spaced apart from the front track 115 to form the aisle 20.The vehicles 200 may move within the aisle 20 along the track. Forinstance, the vehicle may be supported by one or more front wheels thatengage the front track 115 and one or more rear wheels that engage therear track 120.

Each storage rack 35, 40 provides a plurality of storage locations 50for storing containers 80 that store various items. The vehicles movealong the track 110 to storage locations. At a storage location 50, avehicle can transfer an item from the vehicle into one of the storagelocations. Similarly, the vehicle can transfer an item from one of thestorage locations onto the vehicle. Additionally, the system may beconfigured so that the vehicle transfers an item from the vehicle to astorage location while at the same time transferring an item from adifferent storage location onto the vehicle. The storage locations maybe arranged as an array of locations adjacent the aisle. Additionally,as discussed further below, the racks 35, 40 may provide storage depthso that the storage containers may be stored two or more deep toincrease the storage density of the storage containers 80 in the racks.

Storage Racks

The details of the storage rack 35, 40 and the storage locations in thestorage racks will now be described in greater detail. Referring to FIG.1, the system may include one or more storage racks 35, 40. Each storagerack may provide an array of destination areas or storage locations 50for receiving items. The storage locations 50 may be arranged incolumns, however, the storage locations may be arranged in any of avariety of configurations, such as rows. In the following description,the system is described as delivering and/or retrieving items to andfrom storage areas 50. The items may be configured so that an individualitem is stored at a storage location. However, in a typical operationenvironment, the items are stored in or on a storage mechanism, such asa container or platform.

Referring now to FIGS. 8-12, the storage racks 35, 40 and in particular,the storage locations 50 will be described in greater detail. Thestorage locations 50 can be any of a variety of configurations. Forinstance, the simplest configuration is a shelf for supporting the itemsor the container holding the items. Similarly, the storage locations 50may include one or more brackets that cooperate with the storagemechanism to support the storage mechanism in the storage location.

As shown in FIGS. 8 and 11-12, the rack 35 may include a plurality ofvertical supports, such as vertical beams, interconnected with aplurality of horizontal supports, such as horizontal beams. In thepresent instance, the track 110 may form part of the vertical andhorizontal support beams. For instance, the rack 35 may comprise anarray of columns, with each column formed by a plurality of supports.Each column may be defined by two front vertical support beams and tworear vertical support beams. As shown in FIG. 11, the front verticalbeams may comprise the vertical legs 130 of the track. Each column mayinclude a plurality of storage areas 50. In particular, each column isseparated into a plurality of storage areas or cells 50. Each cellincludes a support element for supporting a container to that thecontainer can be stored in the cell. The support elements may be any ofa variety of elements for supporting a container in the storagelocation. For instance, each storage location may include a shelf orother horizontal support onto which a container may be placed. Forinstance, as shown in FIGS. 8 and 11-12, the rack 35 may include aplurality of brackets, such as L-channels 52 attached to the verticalsupports 130. The brackets 52 may extend substantially the depth of eachstorage location 50. In this way, each storage location 50 may bedefined as the area extending between adjacent vertical supports andextending upwardly from adjacent a pair of horizontal supports elements52 to a point adjacent an upper pair of horizontal supports or the topof the rack.

Additionally, as shown in FIG. 11, each storage location 50 may beconfigured so that the containers 80 project inwardly toward the aisleso that the inner end of the container projects inwardly beyond thevertical supports. In other words, the containers 80 may be stored inthe storage locations 50 so that the inner edge of the container (withrespect to the aisle 20) overhands into the aisle.

Referring now to FIG. 9, the racks may be configured so that one or moreof the storage locations 50 is deep enough to accommodate a plurality ofcontainers. For example, one or more of the storage locations are atleast approximately twice as deep as the storage containers 80 so thattwo storage containers can be stored, with one storage container storedbehind the other storage container. It should be understood that thestorage locations may be configured to accommodate any number of storagecontainers. For instance, the racks 35, 40 may be configured so that oneor more of the storage locations can accommodate three containers, sothat the containers are three-deep. In such an embodiment, the storagelocation 50 is approximately three times as deep as the length of thestorage container 80. Similarly, the depth of the rack can be increasedto be approximately “n” times the length of the storage containers toaccommodate “n” storage containers stored “n” deep, wherein “n” is aninteger.

In the exemplary arrangement of FIG. 9, the system is illustrated inconnection with an arrangement for storing containers in a “n” deeparrangement, in which “n”=2. Although the apparatus may include only asingle rack on one side, in FIG. 9, the system is illustrated with tworacks, front rack 35 and rear rack 40. Additionally, each rack isillustrated as being configured to accommodate containers in a two-deeparrangement. However, it should be understand that the racks 35, 40 donot need to be configured to accommodate the same number of containers.For instance, the front rack may be configured as a two-deep rack andthe rear rack 40 may be configured as a single deep rack.

In the following discussion, the storage locations will be describedrelative to the arrangement illustrated in FIGS. 8-9. Each storagelocation 50 includes an inner storage location 55 and an outer storagelocation 57. Each of the inner and outer storage location 55, 57 isconfigured to accommodate a container 80. The inner storage locations 55are adjacent the aisle 20. The outer storage locations 57 are behind theinner storage locations 55, so that the inner storage location separatesthe outer storage location from the aisle 20 and the vehicle 200. In thepresent instance, the inner storage location 55 has a depth that isapproximately the same as the length of a container 80. Similarly, theouter storage location 57 has a depth that is approximately the same asthe length of the container 80. The outer storage locations 57 may beconsidered remote storage locations because they are separated from theaisle by an inner storage location. In a system having a depth ofgreater than two, the remote locations include storage locations thatare separated from the aisle by an inner storage location and one ormore outer storage locations.

As discussed previously, the system may include a plurality of vehicles200 that are conveyed to the storage locations to transfer items to andfrom the storage locations. In particular, the vehicles 200 may includea loading/unloading mechanism to transfer items into a storage location50 or withdraw an item from the storage location. In an embodiment inwhich the storage containers are stored two or more deep, the system isconfigured so that the vehicles are able to retrieve containers storedin one of the remote storage locations. For instance, each vehicle mayinclude a loading element that extends outwardly to a remote storagelocation to engage a storage container in a remote storage location tomove the container to an inner storage location and/or to load thecontainer onto the vehicle from the remote storage location.Alternatively, a separate mechanism may be utilized to move containersfrom a remote storage location to an inner storage location. Forinstance, the rack may include a drive mechanism operable to drive acontainer toward the aisle from a remote storage location. The drivemechanism may be separately powered or may interact with a drivemechanism from one of the vehicles. Yet another alternative is tointerconnect a container in a remote storage location with an adjacentcontainer such that displacing one of the containers displaces bothcontainers. For instance, a container in a remote storage location maybe releasably connected with a container in an inner storage location.When the container in the inner storage location is moved toward theaisle 20, the container in the remote storage location is displacedtoward the inner storage location.

Referring now to FIGS. 11-14, the storage containers 80 are configuredto connect with adjacent containers. In particular, the storagecontainers are configured to releasably connect with one or moreadjacent containers. For instance, as shown in FIG. 13, a releasableconnector 90 connects two adjacent containers 80A, 80B. The releasableconnector selectively connects the two containers. In this way,displacing container 80A horizontally also displaces container 80B.Additionally, the releasable connector 90 may inhibit relative motion inone direction, while allowing relative motion in a second or transversedirection. For example, the connection may connect containers 80A and80B so that horizontal displacement of one container also displaces theother container. At the same time the releasable connector may beconfigured to allow vertical displacement of one container relative tothe other. In the embodiment illustrated in FIGS. 11 and 13-14, thereleasable connector 90 is configured to permit relative verticaldisplacement to connect or disconnect two adjacent containers asdiscussed further below.

In the following discussion, the details of an exemplary storagecontainer 80 are provided. The container 80 may be similar to a cartonor box without a lid, so that an operator can easily reach into thecontainer to retrieve an item at the picking station. Although thepresent system is described as using containers, it should be understoodthat any of a variety of storage mechanisms can be used, such as palletsor similar platforms. Accordingly, in the following discussion, the termcontainer is intended to include items intended to store and/or supportitems, including, but not limited to a pallet, platform, tray, carton,box, receptacle or similar structure.

The storage container 80 may be rectangular prism having a generallyplanar bottom 83. The bottom 83 is substantially horizontal, forming aplatform for receiving items. The container may also include a pluralityof generally vertical walls extending upwardly from the bottom 83. Forinstance, the container 80 may include generally parallel side walls 82.The container may include a forward wall 84 that projects upwardly fromthe bottom 83. The front face may extend between side walls 82 toconnect the side walls. Additionally, the container may include a rearwall 86 that projects upwardly from the bottom. The rear wall 86 may begenerally parallel with the front wall 84. The rear wall 86 may alsoextend between the side walls 82 to connect the side walls. Accordingly,the walls (82,83,84,86) of the container 80 define an interior space inwhich items can be stored.

The containers 80 may include one or more elements configured tocooperate with the vehicles to transfer the containers onto or off ofthe vehicles 200. For instance, the containers may include a hook,detent, socket, or other physical structure configured to cooperate withthe vehicles. In the present instance, the containers may include aretention slot or groove 88 configured to cooperate with aloading/unloading element 212 of the vehicles. The retention groove 88may be formed in the underside of the container 80, below the bottom 83.The retention groove 88 may be spaced rearwardly from the front face 84of the container as shown in FIGS. 11 and 13. The retention groove 88may extend substantially the entire width of the container. The groovemay also have open ends on both sides 82 as shown in FIGS. 11 and 13 sothat the groove is a through slot. As shown in FIG. 13, the groove mayhave a depth that is deeper than the thickness of the loading/unloadingelement 212 of the vehicle 200 so that the loading/unloading elementremains nested within the groove to drive the container inwardly oroutwardly when the loading/unloading element is displaced horizontally.The container 80 may also include a second groove or slot 88 adjacentthe rearward wall 86. The second groove may be configured substantiallysimilarly to the first wall and may be formed adjacent the rearwardwall, spaced forwardly from the rearward wall 86.

Referring to FIGS. 13-14, a releasable connector 90 is illustrated forreleasably connecting adjacent containers 80A, 80B. The connector 90 mayfacilitate displacement of one of the containers from a remote storagelocation 57 to an inner storage location 55. The releasable connector 90may be cooperating hooks or latches. For instance, the releasableconnector 90 may be formed of a pair of cooperable connectors 92B, 96A.A forward connector 92 may be connected with the forward end 84 of thecontainer 80 and a rearward connector 96 may be connected with therearward end of the container 80. In this way, the forward connector 92Bof a first container 80B is releasably connectable with the rearwardconnector 96A of a second container 80A to connect the two containers.In one embodiment, the forward connector 92 is a hook in the form of atongue extending downwardly generally vertically (see 92B in FIG. 14).The forward connector 92 projects downwardly from a recess adjacent theforward end of the container. In the present instance, the forwardconnector is an L-shaped bracket. The L-shaped bracket may have a bodyportion rigidly and fixedly connected with the bottom of the container.For example, the body portion of the forward connector 92 may extendsubstantially horizontally and may be affixed to the container by afastener extending through the connector 92 and into the container. Thetongue 94 of the forward connector may project transverse the bodyportion so that the tongue projects downwardly to form a vertical hookor flange that engages the second connector 96. As shown in FIG. 13, theforward connector may be connected to the container forwardly of thegroove 88 used to engage the loading/unloading mechanism 212 of thevehicle.

The rearward connector 96 may be a second hook that cooperates with thefirst hook 92. The rearward connector 96 may project rearwardly from therearward end of the container 80. In the present instance, the secondconnector 96 incorporates a hook or flange that projects verticallyupwardly. Specifically, the second connector 96 may comprise a groove orchannel 98 configured to receive the tongue 94 of the first connector92. The channel 98 may be connected to a rearward end 86 of thecontainer 80 so that the channel projects rearwardly from the rearwardend. The second connector may have a body portion rigidly and fixedlyconnected with the bottom of the container. For example, the bodyportion of the rear connector 96 may be a generally flat portionextending substantially horizontally and may be affixed to the containerby a fastener extending through the connector 96 and into the container.

As shown in FIG. 13, the tongue 94B of the forward connector 92B of afirst container 80B is inserted into the slot 98A of the rearwardconnector 96A of the second container 80A to connect the first andsecond containers. As discussed further below, the connection betweenthe two containers allows the containers to move together when one ofthe containers is displaced. In this way, pulling a first container froman inner storage location onto a vehicle pulls a connected containerfrom a remote storage location toward an inner storage location.

Track

As can be seen in FIGS. 1 and 12, a track may be provided adjacent thestorage locations to direct the vehicles 200 to the storage locations.The track 110 may include a front track 115 and a rear track 120 thatare parallel to one another to guide the vehicles around the track. Asshown in FIG. 3, each of the vehicles includes four wheels 220: twoforward wheel and two rearward wheels. The forward wheels 220 ride inthe front track, while the rearward wheel ride in the rear track. Itshould be understood that in the discussion of the track the front andrear tracks 115, 120 are similarly configured opposing tracks thatsupport the forward and rearward wheels 220 of the vehicles.Accordingly, a description of a portion of either the front or reartrack also applies to the opposing front or rear track.

Referring to FIGS. 4-7, the details of the track will be described ingreater detail, however, as noted above, it should be appreciated thatthe illustrated track is merely an exemplary track that can be used withthe system. The precise configuration may vary according to theapplication and as noted above, the system may not include the track.

The track 110 may include an outer wall 152 and an inner wall 154 thatis spaced apart from the outer wall and parallel to the outer wall. Thetrack also may have a back wall 160 extending between the inner andouter walls. As can be seen in FIG. 7, the outer and inner walls 152,154 and the back wall form a channel. The wheels 220 of the vehicle ridein this channel.

The track may include both a drive surface 156 and a guide surface 158.The drive surface positively engages the vehicles to enable the vehicleto travel along the track. The guide surface 158 guides the vehicle,maintaining the vehicle in operative engagement with the drive surface156. In the present instance, the drive surface is formed of a series ofteeth, forming a rack that engages the wheels of the vehicles asdescribed further below. The guide surface 158 is a generally flatsurface adjacent the rack 156. The rack 156 extends approximatelyhalfway across the track and the guide surface 158 extends across theother half of the track. As shown in FIGS. 4-7, the rack 156 may beformed on the inner wall 154 of the track. The opposing outer wall 152may be a generally flat surface parallel to the guide surface 158 of theinner wall.

As described above, the track 110 may include a plurality of verticallegs extending between the horizontal upper and lower rails 135, 140. Anintersection 170 may be formed at each section of the track at which oneof the vertical legs intersects one of the horizontal legs. Eachintersection may include an inner branch 172 that is curved and an outerbranch 176 that is generally straight. The intersections of the verticallegs with the lower rail incorporate similar intersections, except theintersections are reversed.

Each intersection 170 may include a pivotable gate 180 that may have asmooth curved inner race and a flat outer race that has teeth thatcorrespond to the teeth of the drive surface 156 for the track. The gate180 may pivot between a first position and a second position. In thefirst position, the gate 180 is closed so that the straight outer race184 of the gate is aligned with the straight outer branch 176 of theintersection. In the second position, the gate is open so that thecurved inner race 182 of the gate is aligned with the curved branch 172of the intersection.

Accordingly, in the closed position, the gate is pivoted downwardly sothat the outer race 184 of the gate aligns with the drive surface 156.In this position, the gate blocks the vehicle from turning down thecurved portion, so that the vehicle continues straight through theintersection. In contrast, as illustrated n FIG. 6, when the gate ispivoted into the open position, the gate blocks the vehicle from goingstraight through the intersection. Instead, the curved inner race 182 ofthe gate aligns with the curved surface of the inner branch 172 and thevehicle turns through the intersection. In other words, when the gate isclosed, a vehicle goes straight through the intersection along eitherthe upper rail 130 or the lower rail, depending on the location of theintersection. When the gate is opened, the gate directs the vehicle fromeither a vertical rail to a horizontal rail or from a horizontal rail toa vertical rail, depending on the location of the intersection.

In the foregoing description, the gates allow one of the vehicles toeither continue in the same direction (e.g. horizontally) or turn in onedirection (e.g. vertically). However, in some applications, the systemmay include more than two horizontal rails that intersect the verticalcolumns. In such a configuration, it may be desirable to include adifferent rail that allows the vehicles to turn in more than onedirection. For instance, if a vehicle is traveling down a column, thegate may allow the vehicle to turn either left or right down ahorizontal rail, or travel straight through along the vertical column.Additionally, in some instances, the vehicles may travel upwardly.

Since the system 10 includes a number of vehicles 200, the positioningof the vehicles is controlled to ensure that the different vehicles donot crash into each other. In one embodiment, the system 10 uses acentral controller that tracks the position of each vehicle 200 andprovides control signals to each vehicle to control the progress of thevehicles along the track. The central controller may also controloperation of the various elements along the track, such as the gates180. Alternatively, the gates may be actuated by the vehicles 200. Forinstance, referring to FIGS. 4-5, the gates 180 may include a passiveactuator 190 that responds to an actuator 230 on the vehicles. If theactuator on the vehicle engages the gate actuator 190 then the gatemoves from a first position to a second position. For instance, as shownin FIG. 4, the gate is in a first position so that the vehicle willremain along the horizontal rail 135. If the gate actuator 230 on thevehicle 200 engages the actuator 190 on the gate, the gate 180 willpivot upwardly into a second position so that the vehicle will turn andmove downwardly along the vertical rail 130.

The actuators 190 on the gates may be moveable actuation surfaces 192connected to the gate by a linkage. For instance, the actuation surface192 may be mounted on a pivotable arm 193. To actuate the gate and moveit from the first position to the second position, the gate actuator 230on the vehicle contacts the actuation surface 192. The actuation surfaceis angled similar to a ramp, so that as the vehicle advances toward thegate, the gate actuator on the vehicle engages the actuation surface andprogressively displaces the arm 193 upwardly. The arm 193 may beconnected to the gate 180 by a linkage. Accordingly, when the arm 193pivots, the gate pivots as well. In this way, the actuator 230 on thevehicle engages the actuator on the gate to move the gate from the firstposition to the second position as shown in FIGS. 4-5. After the vehicle200 passes an open gate, such as shown in FIG. 5, the gate may return tothe closed position shown in FIG. 4. The gate may close automatically,such as by a biasing element or the weight of the gate and/or actuator.

Delivery Vehicles

Referring to FIG. 3, the details of the delivery vehicles 200 will bedescribed in greater detail. Each delivery vehicle is a semi-autonomousvehicle that may have an onboard drive system, including an onboardpower supply. Each vehicle may also include a mechanism for loading andunloading items for delivery. Optionally, each vehicle may also includea gate actuator 230 for selectively actuating the gates 180 to allow thevehicle to selectively change direction.

The vehicle 200 may incorporate any of a variety of mechanisms forloading an item onto the vehicle and discharging the item from thevehicle into one of the bins. Additionally, the loading/unloadingmechanism 210 may be specifically tailored for a particular application.In the present instance, the loading/unloading mechanism 210 maycomprise a displaceable element configured to engage an item stored at astorage location 190 and pull the item onto the vehicle. Morespecifically, in the present instance, the vehicle includes adisplaceable element configured to move toward a container 80 in astorage location 50. After the displaceable element engages thecontainer 80, the displaceable element is displaced away from thestorage location 50, thereby pulling the container onto the vehicle 200.

In the present instance, the loading/unloading mechanism 210 maycomprise a displaceable rod or bar 212. The bar 212 may extend acrossthe width of the vehicle 200 and both ends may be connected with drivechains that extend along the sides of the vehicle. A motor may drive thechains to selectively move the chain toward or away from storagelocations. For example, as the vehicle approaches a storage location toretrieve a container 80, the chain may drive the rod 212 toward thestorage location so that the bar engages a groove or notch 88 in thebottom of the container 80. The chain then reverses so that the bar 212moves away from the storage location 50. Since the bar is engaged in thenotch 88 in the container, as the bar moves away from the storagelocation, the bar 212 pulls the container onto the vehicle. In this way,the loading/unloading mechanism 210 may be operable to retrieve itemsfrom a storage location. Similarly, to store an item in a storagelocation 50, the chain of the loading/unloading mechanism 210 drives thebar 212 toward the storage location until the item is in the storagelocation. The vehicle may then moves downwardly to disengage the barfrom the container 80, thereby releasing the container. Alternatively,the loading/unloading mechanism may be configured so that the bar 212 isdriven downwardly, out of engagement with the notch 88.

Additionally, since the system 10 includes an array of storage locations50 adjacent the front side of the track 110 and a second array ofstorage locations adjacent the rear side of the track, theloading/unloading mechanism 210 is operable to retrieve and store itemsin the forward array and the rearward array. Specifically, as shown inFIG. 3, the loading/unloading mechanism 210 includes two bars spacedapart from one another. One bar is operable to engage containers in theforward array, while the second bar is operable to engage containers inthe rearward array of storage locations.

The vehicle 200 may include four wheels 220 that are used to transportthe vehicle along the track 110. The wheels 220 may be mounted onto twoparallel spaced apart axles 215, so that two of the wheels are disposedalong the forward edge of the vehicle and two of the wheels are disposedalong the rearward edge of the vehicle.

The vehicle may include an onboard motor for driving the wheels 220.More specifically, the drive motor may be operatively connected with theaxles to rotate the axles 215, which in turn rotates the gears 222 ofthe wheels. The drive system for the vehicle may be configured tosynchronously drive the vehicle along the track. In the presentinstance, the drive system is configured so that each gear is driven ina synchronous manner.

The vehicle 200 may be powered by an external power supply, such as acontact along the rail that provides the electric power needed to drivethe vehicle. However, in the present instance, the vehicle includes anonboard power source that provides the requisite power for both thedrive motor and the motor that drives the load/unload mechanism 210.Additionally, in the present instance, the power supply is rechargeable.Although the power supply may include a power source, such as arechargeable battery, in the present instance, the power supply is madeup of one or more ultracapacitors. The ultracapacitors can accept veryhigh amperage to recharge the ultracapacitors. By using a high current,the ultracapacitors can be recharged in a very short time, such as a fewseconds or less.

The vehicle includes one or more contacts for recharging the powersource. In the present instance, the vehicle includes a plurality ofbrushes, such as copper brushes that are spring-loaded so that thebrushes are biased outwardly. The brushes cooperate with a charging railto recharge the power source.

Each vehicle may include a load sensor for detecting that an item isloaded onto the vehicle. The sensor(s) may be used to detect whether theitem is properly positioned on the vehicle. For instance, the loadsensor may include a force detector detecting a weight change or aninfrared sensor detecting the presence of an item.

The vehicle may further include a processor for controlling theoperation of the vehicle in response to signals received from a centralprocessor of the system. Additionally, the vehicle may include awireless transceiver so that the vehicle can continuously communicatewith the central processor as it travels along the track. Alternatively,in some applications, it may be desirable to incorporate a plurality ofsensors or indicators positioned along the track. The vehicle mayinclude a reader for sensing the sensor signals and/or the indicators,as well as a central processor for controlling the operation of thevehicle in response to the sensors or indicators.

Pick Station and Track

As described previously, the system 10 may be configured so that thevehicles 200 retrieve items from the storage locations 50 and transportthe items to the pick station 300. Referring now to FIGS. 1-2 the pickstation 300 will be described in greater detail.

In one mode of operation, the system 10 is used to retrieve items neededto fill an order. The order may be an internal order, such as partsneeded in a manufacturing process in a different department, or theorder may be a customer order that is to be filled and shipped to thecustomer. Either way, the system automatically retrieves the items fromthe storage areas and delivers the items to the picking station so thatan operator can pick the required number of an item from a container.After the item is picked from a container, the vehicle advances so thatthe next item required for the order is advanced. The system continuesin this manner so that the operator can pick all of the items needed foran order.

In the present instance, the pick station 300 is positioned at one endof the array of storage locations. However, it may be desirable toincorporate multiple pick stations positioned along the track 110. Forinstance, a second pick station can be positioned along the opposite endof the array of storage locations. Alternatively, multiple pick stationscan be provided at one end. For instance, a second pick station may bepositioned above a first pick station at one end of the aisle.

The pick station 300 may be configured so that the vehicle travelsupwardly to present the contents to the operator so that the operatorcan more easily retrieve items from the container 80. Referring to FIGS.1-2, at the picking station the track includes a curved section 315 thatbends upwardly and away from the operator. In this way, the vehiclemoves upwardly and then stops at a height that facilitates the operatorremoving items from the container. After the operator removes items fromthe container, the vehicle moves laterally away from the operator andthe vertically to the upper horizontal rail 135.

The system can be configured so that the vehicles tilt at the pickstation 300 thereby making it easier for the operator to retrieve itemsfrom the container. For instance, as the vehicle approaches the pickstation, the controller may control the vehicle so that the rearward setof wheels continue to drive after the forward set of wheel stop. Thisraises the rearward edge of the vehicle (from the perspective of theoperator). After the operator picks the items from the container, theforward set of wheels (relative to the operator) drive first, therebylevel off the vehicle. Once leveled, the four wheels drivesynchronously.

Although the vehicles may be tilted by controlling operation of thevehicles, if the wheels of the vehicles positively engage drive elementsin the track, such as the toothed wheels 220 that mesh with teeth in thetrack as described above, the wheels 220 may bind if the rear wheels aredriven at a different rate than the forward wheels. Accordingly, thetrack system may be modified so that the track moves to tilt thecontainer toward the operator.

Referring to FIGS. 1 and 2, the details of the track system in thepicking station 300 will be described in greater detail. At the end ofthe columns of storage locations, the track curves outwardly away fromthe vertical columns of the system to form the curved track 315 of thepick station 300. The track sections of the pick station includeparallel forward track sections that support and guide the forward axle215 of the vehicles 200 and parallel rearward track sections thatsupport and guide the rear axle 215 of the vehicles. The forward tracksections extend vertically upwardly and then curve back toward thevertical columns of storage locations. The rearward track sections aresubstantially parallel to the forward track sections and curvesubstantially similarly to the forward track sections. In this way, theforward and rearward track sections guide the vehicles so that thevehicles can maintain a substantially horizontal orientation as thevehicles are driven along the curved track 315.

The rearward track sections may be configured so that the rearward axleof the vehicle 200 can be lifted while the vehicle is stopped at thepick station 300. By lifting the rearward axle of the vehicle 200, thecontainer on the vehicle is tilted to present the contents of thecontainer to the operator to facilitate the picking process.

The pick station 300 may include a plurality of items to improve theefficiency of the pick station. For instance, the pick station mayinclude a monitor to display information to aid the operator. As thevehicle approaches the pick station, the system 10 may displayinformation such as how many items need to be picked from the containerfor the order. Additionally, since the operator may pick items formultiple orders, the system may display which order(s) the item is to bepicked for, in addition to how many of the item are to be picked foreach order. The system may also display information such as how manyitems should be remaining in the container after the operator picks theappropriate number of items from the container.

One feature of the system as described above is that the orientation ofthe vehicles does not substantially change as the vehicles move fromtravelling horizontally (along the upper or lower rails) to vertically(down one of the columns). Specifically, when a vehicle is travellinghorizontally, the two front geared wheels 220 cooperate with the upperor lower horizontal rail 135 or 140 of the front track 115, and the tworear geared wheels 220 cooperate with the corresponding upper or lowerrail 135 or 140 of the rear track 120. As the vehicle passes through agate and then into a column, the two front geared wheels engage a pairof vertical legs 130 in the front track 115, and the two rear gearedwheels engage the corresponding vertical legs in the rear track 120. Itshould be noted that when it is stated that the orientation of thevehicles relative to the horizon do not change, this refers to thetravel of the vehicles around the track. Even though the vehicles maytilt relative to the horizon at the picking station, the vehicles arestill considered to remain in a generally constant orientation relativeto the horizon as the vehicles travel along the track 110.

As the vehicle travels from the horizontal rails to the vertical columnsor from vertical to horizontal, the tracks allow all four geared wheelsto be positioned at the same height. In this way, as the vehicle travelsalong the track it does not skew or tilt as it changes between movinghorizontally and vertically. Additionally, it may be desirable toconfigure the vehicles with a single axle. In such a configuration, thevehicle would be oriented generally vertically as opposed to thegenerally horizontal orientation of the vehicles described above. In thesingle axle configuration, the weight of the vehicles would maintain theorientation of the vehicles. However, when using a single axle vehicle,the orientation of the storage locations would be re-configured toaccommodate the vertical orientation of the vehicles.

Operation

Once the central controller determines the appropriate storage location50 for the item, the route for a vehicle leaving the pick station 300may be determined. Specifically, the central controller may determinethe route for the vehicle and communicates information to the vehicleregarding the storage location into which the item is to be delivered.The central controller may then control the operation of the vehicle toactuate gates along the track as necessary to direct the vehicle to thestorage location into which the item is to be delivered. Once thevehicle reaches the appropriate storage location, the vehicle stops atthe storage location 50 and the container is displaced into theappropriate storage location. For example, the vehicle may be stopped atthe appropriate storage location 100 and the onboard controller on thevehicle may send an appropriate signal to the vehicle to drive the chain214, which advances the bar 212. Since the bar 212 is engaged in theslot 88 in the container, the bar drives the container off the vehicleand into the appropriate storage location.

After discharging the item, the vehicle 200 may travel to a secondstorage location to retrieve the next item to be transported to thepicking station. After retrieving the item, the vehicle 200 may traveldown the vertical legs 130 of the column until it reaches the lower rail140. Gates may direct the vehicle along the lower rail, and the vehiclemay follow the lower rail to return to the pick station 300 to deliveranother item.

If the vehicle 200 delivers a container to an empty storage location,then the operation of the vehicle proceeds as described above.Similarly, if the vehicle retrieves a container 80 that is not connectedwith another container, then the operation of the vehicle proceeds asdescribed. In particular, the vehicle stops adjacent the container. Theloading/unloading mechanism advances into engagement with the containerand then the loading/unloading mechanism pulls the container onto thevehicle. In contrast, the operation of the vehicle is modified if thevehicle carries a container to be placed in a storage location thatalready contains a container. Similarly, the operation of the vehicle ismodified if the vehicle is retrieving a container attached to acontainer in a remote storage location.

Referring now to FIGS. 9 and 10A-10H, the operation of vehicle inretrieving a container from a storage location having “n” deepcontainers will be described. FIG. 9 illustrates an exemplary embodimentin which two racks 35, 40 of storage containers 80 are illustrated. Theracks 35, 40 are separated from one another by an aisle and the vehicle200 travels within the space between the racks. In the illustratedembodiment, the rack includes storage locations that have a depthsufficient to store two storage containers. The portion of the storagelocation that accommodates the storage container adjacent the aisle isreferred to in this discussion as the inner cell and is designated 55.The portion of the storage location behind the inner cell 55 is referredto as the remote cell and is designated 57.

In the illustrated embodiment, each container includes a front connector92 connected to the front end of the container and a rear connector 96connected to a rear end of the container. The front connector of thecontainer in the remote cell connects with rear connector of thecontainer in the inner cell to create a releasable connection designated90.

In FIG. 9, storage container 80A is stored in a remote cell behindstorage container 80B that is stored in an inner cell. Containers 80A,80B are releasably connected to one another by a connector, such asconnector 90. The containers 80A, 80B are generally aligned from ahorizontal perspective. The vehicle 200 is stopped at a positionadjacent the storage location that houses container 80A. The vehicle 200is empty (i.e. no container is loaded on the vehicle). The load/unloadmechanism 210 engages the container 80A as shown in FIG. 9. For example,as shown in FIGS. 11 and 12, the front edge of the container 80 mayextend into the aisle beyond the track (e.g. vertical track sections130). In particular, the transfer groove 88 of the container 80 mayextend into the aisle. The load bar 212 extends outwardly toward thecontainer, away from the platform of the vehicle until the load bar isinserted into the transfer groove 88.

Referring to FIG. 10A, the load mechanism pulls the container 80A ontothe vehicle 200. As the container 80A in the inner cell is pulled ontothe vehicle, the container 80A pulls the container 80B in the remotecell toward the inner cell. In particular, the connector 90 connects theinner and remote containers 80A, 80B so that the containers movehorizontally together.

Referring to FIG. 10B, vehicle continues to displace the container 80Aonto the platform of the vehicle until the container is clear of thecontainer in the storage location above the container. The displacementof container 80A pulls the remote container 80B into the inner cell sothat container 80B has taken the place that container 80A had in therack. It can be seen in FIG. 10B that by pulling container 80B into theinner cell, the remote cell 57 behind container 80B is now vacant.

As described above, the loading mechanism 210 of the vehicle loads theinner container 80A onto the vehicle, which in turns displaces theremote container 80B horizontally until the remote container is movedinto a different storage locations, which in this instance is an innercell. Continued displacement of the container 80A onto the vehicle wouldpull container 80B into the aisle and potentially onto the vehiclebecause the two containers remain connected. Accordingly, once thecontainer 80B is displaced into the new storage location (i.e. the innercell), the releasable connection 90 disconnects to thereby disconnectthe two containers 80A, 80B.

Containers 80A, 80B may be disconnected in a variety of ways, dependingon the mechanism that interconnects the containers. As noted previously,the connectors 92, 96 may be any of a variety of connectors that providea releasable connection between two containers. The connectors may bemechanical or electro-mechanical. For example, the connectors 92, 96could be magnetic elements, one of which may comprise an electro-magnet.The electro-magnet may be de-energized to disconnect the containers tofacilitate relative motion of the first container relative to the secondcontainer. Alternatively, as described above, the connectors 92, 96 maybe mechanical connectors, such as a pair of hooks or a tongue and groovearrangement. Accordingly, to disconnect the containers 80A, 80B, theconnectors 92, 96 are disengaged. In one embodiment, the connectors 92,96 are disengaged by displacing one of the containers verticallyrelative to the other container.

Referring to FIG. 10C, once the first container 80A is loaded onto thevehicle so that the container 80A is clear of the containers immediatelyabove it or below it in the column, the container 80A is displacedvertically to disconnect container 80A from container 80B. As shown inFIGS. 13-14, the tongue 94B of connector 92B may project downwardly intothe groove 98A of connector 96A. Therefore, the vehicle moves downwardlyto vertically displace container 80A downwardly until the tongue 94B ofconnector 92B disengages the groove 98A as shown in FIG. 14. In thisway, displacing the vehicle 200 vertically disconnects container 80Afrom container 80B. It should be understood, that the connectors 92, 96may be configured differently so that the connectors are disconnected bymoving the vehicle upwardly, rather than lowering the vehicle.

Referring now to FIG. 10D, after the first container 80A is disconnectedfrom the second container 80B, the container 80A is displacedhorizontally on the vehicle away from the second container. The firstcontainer is displaced horizontally until is centered within the aislesuch that the container is clear from interfering or engaging any of thevehicles in the rack when the vehicle moves vertically upwardly ordownwardly in the column. Once the container 80A is completely loadedonto the vehicle, the vehicle may advance toward the picking station 300or other transfer location or to a different storage location. Forexample, the vehicle may move down to the lower horizontal rail and thenalong the horizontal rail to deliver container 80A to the pickingstation 300. Alternatively, the container 80A may be transported toanother storage location and unloaded into the storage location.

The details of the steps of unloading the container 80A on vehicle 200into a storage location in which a third container designated 80C islocated are described below in connection with FIGS. 10E-10H. Thevehicle 200 moves into position adjacent an inner cell in rack 40 inwhich container 80C is stored. The container 80A is unloaded from thevehicle toward the third container 80C. As the container 80A isunloaded, the container 80A pushes the third container 80C deeper intothe storage location in the rack. Doing so displaces container 80Chorizontally from the inner cell into the remote cell 57. During theprocess of unloading the first container 80A and displacing container80C, the first container 80A is connected to the third container 80C. Asdescribed previously, the connectors of the two containers may beconnected in a variety of ways. In the present instance, the containersare connected by moving one of the containers relative to the other.Specifically, the first container 80A is displaced vertically relativeto the third container 80C to connect the two containers.

Referring again to FIG. 10E, to unload the first container 80A, thevehicle is displaced along the track until the first container 80A isdisposed vertically higher than the third container 80C. In particular,the vehicle is driven to a position adjacent the container so that thefront connector of the first container is positioned above the rearconnector of the third container 80C. The first container is thendisplaced horizontally toward the third container 80C to partiallyunload the container from the vehicle, as shown in FIG. 10F. In thepresent instance, the first container is displaced until the frontconnector of the first container is aligned with the rear connector ofthe third container 80C. In particular, the unloading mechanism 210 ofthe vehicle displaces the container 80A horizontally until the tongue 94of the front connector 92 is aligned with the groove 98 of the rearconnector 96 on the third container 80C.

Once the connectors of container 80A and 80C are aligned, the vehiclemoves vertically to connect the containers. Specifically, referring toFIG. 10G, the vehicle moves downwardly to horizontally align containers80A and 80C and to interconnect the two containers. Once the firstcontainer 80A is aligned horizontally with the storage location, thefirst container is unloaded from the vehicle into the storage locationas shown in FIG. 10H. For instance, in the present embodiment, theloading/unloading mechanism of the vehicle drives the first container80A off of the vehicle and into the inner cell in which the thirdcontainer 80C was located. As the first container is driven into theinner cell, the first container 80A pushes the third container 80Cdeeper into the storage location so that the third container is movedinto the remote cell (designated 57 in FIG. 10G).

As described above, the first container 80A is moved into positionadjacent the third container 80C. The two containers are then connectedbefore unloading the first container into the storage rack. In this way,the containers are linked so that subsequently, the third container inthe remote cell can be pulled toward the aisle when the first container80A is retrieved (see e.g. FIGS. 10A-10D and description above).However, it should be appreciated that the containers do not need to beconnected in order to unload the first container and move the thirdcontainer into the remote cell. Specifically, since the first container80A pushes the third container 80C rearwardly into the rear cell, thecontainers do not need to be connected prior to unloading the firstcontainer. Therefore, depending on the configuration of the front andrear connectors, the containers may be connected to one another afterthe first container is unloaded from the vehicle.

Accordingly, as described above, the system may be configured toincorporate multi-depth storage locations in which containers are storedbehind one another in a common horizontal storage location. Thecontainers in a common horizontal storage location may be interconnectedso that retrieving one of the containers in the common storage locationdisplaces the other containers in the common storage location forwardlytoward the vehicle. In the above description, the operation has beendescribed in which a first container is loaded onto a delivery vehicle,thereby pulling a container from a remote cell into an inner cell sothat the container can be retrieved from the inner cell. The vehicle canthen deliver the first container to a different storage locations andthen return to retrieve the second container that was displaced into theinner cell. Alternatively, in certain instance, a storage locationhousing two containers (such as containers 80A and 80B shown in FIG. 9)may be located across from an open storage location vertically andhorizontally aligned with the two containers. In such an instance, thefirst container 80A may be loaded onto the vehicle, thereby pulling thesecond container toward the vehicle. Rather than disconnecting the twocontainers as described above, the first container 80A is furtherdisplaced horizontally to unload the container into a storage locationin the opposing rack. As the first container 80A is unloaded into thestorage location, the second container 80B is pulled onto the vehicle.The second container can then be disconnected from the first containerso that the vehicle can deliver the second container to the pickingstation or a different storage location. For instance, the vehicle canbe displaced vertically to disconnect the second container from thefirst container.

In the foregoing description, a system is described in which containersare stored in multi-depth storage locations. A container in a remotecell of a multi-depth storage location may be retrieved by a vehiclefirst retrieving a container that is in front of the container in theremote cell. The retrieved container is then transported away by thevehicle. The retrieved container may then be stored in a differentlocation so that the vehicle can return to retrieve the container thatwas located in the remote cell. Alternatively, a first vehicle mayretrieve the container that is in front of the container in the remotecell and a second vehicle may come and retrieve the vehicle that waslocated in the remote cell.

It will be recognized by those skilled in the art that changes ormodifications may be made to the above-described embodiments withoutdeparting from the broad inventive concepts of the invention. It shouldtherefore be understood that this invention is not limited to theparticular embodiments described herein, but is intended to include allchanges and modifications that are within the scope and spirit of theinvention as set forth in the claims.

What is claimed is:
 1. A material handling system for storing orretrieving a plurality of storage containers, comprising: a plurality ofvehicles for delivering and retrieving storage containers, wherein eachvehicle comprises an on-board motor for driving the vehicle; a firstrack of storage locations; a second rack of storage locations spacedapart from the first rack with an aisle between the first and secondracks; wherein the vehicles are displaceable in a vertical directionwithin the aisle and horizontally transverse the vertical direction; aplurality of storage locations wherein each storage location isconfigured to receive a plurality of the storage containers; wherein afirst of the storage containers comprises a first connector at a firstend and a second of the storage containers comprises a second connectorat a second end, wherein the first connector is releasably connectablewith the second connector to releasably connect the first and secondstorage containers at one of the storage locations; wherein each vehiclecomprises a transfer mechanism configured to displace the first andsecond storage containers between the vehicle and the one storagelocation wherein the releasable connection between the first and secondcontainers is operable to displace the second storage container when thetransfer mechanism displaces the first storage container.
 2. Theapparatus of claim 1 comprising a track for guiding the vehicles,wherein the track comprises: a plurality of horizontal track sectionsspaced apart from one another and extending in a generally horizontaldirection; a plurality of vertical track sections spaced apart from oneanother and extending in a generally vertical direction, wherein thevertical track sections intersect the horizontal track sections to forma loop; and an intersection where one of the horizontal track sectionsintersects one of the vertical track sections, wherein the intersectionprovides a first path in a generally horizontal direction and a secondpath in a generally vertical direction.
 3. The apparatus of claim 1wherein the connection of the first and second connectors impedeshorizontal displacement of the first container relative to the secondcontainer.
 4. The apparatus of claim 3 wherein the connection of thefirst and second connectors is sufficient to support the weight of thesecond container during horizontal displacement such that displacing thefirst container horizontally displaces the second container horizontallywhen the first and second connectors are connected.
 5. The apparatus ofclaim 3 wherein the connection of the first and second connectorspermits vertical displacement of the first container relative to thesecond container.
 6. The apparatus of claim 5 wherein the first andsecond connectors are configured such that vertical displacement of thevehicle along the track disconnects the first and second connectors. 7.The apparatus of claim 3 wherein the first and second connectors areconfigured such that displacement of the first connector verticallyrelative to the second connector disconnects the first connector fromthe second connector.
 8. The apparatus of claim 1 wherein the firstconnector comprises a tongue and the second connector comprises a grooveconfigured to receive the tongue.
 9. The apparatus of claim 1 whereinthe storage location in which the first and second containers arelocated is configured to house the first and second containers inhorizontal alignment wherein the first container is positioned in frontof the second container.
 10. The apparatus of claim 9 wherein when oneof the vehicles is aligned with the first container, the first containerseparates the second container from the vehicle.
 11. The apparatus ofclaim 1 wherein the one of the storage locations has a depth and thefirst and second container each have a length, wherein the depth of theone storage location is at least as long as the combined length of thefirst and second containers.
 12. The apparatus of claim 1 wherein thevehicles comprise a generally planar platform for receiving thecontainers.
 13. The apparatus of claim 1 wherein a pick station isdisposed at an end of the aisle, wherein the vehicles deliver containersto the pick station so that operators can retrieve items from thecontainers at the pick station.
 14. The apparatus of claim 2 wherein thevehicles comprise drive wheels that engage the track and wherein theracks are positioned relative to the track so that the containersproject horizontally into the aisle beyond the track.
 15. The apparatusof claim 1 wherein the containers contain one or more engagementelements configured to engage the transfer mechanism of the vehicles.16. A material handling system for storing or retrieving a plurality ofstorage containers, comprising: a plurality of independently operablevehicles for delivering and retrieving storage containers, wherein eachvehicle comprises an on-board motor for driving the vehicle; a firstrack of storage locations wherein a plurality of the storage locationsare vertically spaced apart from one another forming a first verticalcolumn; a second rack of storage locations wherein a plurality of thestorage locations are vertically spaced apart from one another forming asecond vertical column spaced apart from the first vertical column withan aisle between the first and second vertical columns; a trackconfigured to guide the vehicles to the storage locations; wherein thevehicles are displaceable in the aisle in a vertical direction along thetrack and displaceable horizontally transverse the vertical direction; aplurality of storage containers wherein each storage location isconfigured to receive a plurality of the storage containers so that afirst container positioned in a first storage location is adjacent theaisle and a second container positioned in the first storage location isspaced from the aisle by the first container; wherein the first storagecontainers comprise a first connector at a first end and the second thestorage containers comprises a second connector at a second end, whereinthe second connector is releasably connectable with the first connectorto releasably connect the first and second storage containers at thefirst storage location; wherein each vehicle comprises a transfermechanism configured to displace the first and second storage containersbetween the vehicle and the first storage location wherein thereleasable connection between the first and second containers isoperable to displace the second storage container when the transfermechanism displaces the first storage container.
 17. The apparatus ofclaim 16 wherein the track comprises: a plurality of horizontal tracksections spaced apart from one another and extending in a generallyhorizontal direction; a plurality of vertical track sections spacedapart from one another and extending in a generally vertical direction,wherein the vertical track sections intersect the horizontal tracksections to form a loop; and an intersection where one of the horizontaltrack sections intersects one of the vertical track sections, whereinthe intersection provides a first path in a generally horizontaldirection and a second path in a generally vertical direction.
 18. Theapparatus of claim 16 wherein the connection of the first and secondconnectors impedes horizontal displacement of the first containerrelative to the second container.
 19. The apparatus of claim 18 whereinthe connection of the first and second connectors is sufficient tosupport the weight of the second container during horizontaldisplacement such that displacing the first container horizontallydisplaces the second container horizontally when the first and secondconnectors are connected.
 20. The apparatus of claim 18 wherein theconnection of the first and second connectors permits verticaldisplacement of the first container relative to the second container.21. The apparatus of claim 20 wherein the first and second connectorsare configured such that vertical displacement of the vehicle along thetrack disconnects the first and second connectors.
 22. The apparatus ofclaim 18 wherein the first and second connectors are configured suchthat displacement of the first connector vertically relative to thesecond connector disconnects the first connector from the secondconnector.
 23. The apparatus of claim 16 wherein the first connectorcomprises a tongue and the second connector comprises a grooveconfigured to receive the tongue.
 24. The apparatus of claim 16 whereinthe first storage location is configured to house the first and secondcontainers in horizontal alignment wherein the first container ispositioned in front of the second container.
 25. The apparatus of claim16 wherein the first storage location has a depth and the first andsecond container each have a length, wherein the depth of the firststorage location is at least as long as the combined length of the firstand second containers.
 26. The apparatus of claim 16 wherein thevehicles comprise a generally planar platform for receiving thecontainers.
 27. The apparatus of claim 16 wherein the vehicles comprisedrive wheels that engage the track and wherein the racks are positionedrelative to the track so that the containers project horizontally intothe aisle beyond the track.
 28. The apparatus of claim 16 wherein thecontainers contain one or more engagement elements configured to engagethe transfer mechanism of the vehicles.